The present invention belongs to the technical field of liquid ejection apparatus utilized in inkjet recording heads, etc. and, more particularly, relates to a liquid ejection apparatus that is high in production efficiency and yield and, in addition, can realize ejection of liquid droplets with a high accuracy, a method of manufacturing this liquid ejection apparatus, an inkjet printer utilizing this liquid ejection apparatus, and a method of manufacturing this inkjet printer.
Thermal inkjet formed in such a manner that a portion of ink is rapidly vaporized by heating by the use of a heater, so that, by the expansion force thereof, etc., ink droplets are ejected from nozzles, is utilized in various printers (See JP 48-9622 A, JP 54-51837 A, etc.).
Further, there is also known a printer that utilizes an electrostatic type inkjet formed in such a manner that a diaphragm (vibration plate) is vibrated by static electricity, so that, by the energy thereof, ink droplets are ejected from nozzles (See JP 11-309850 A, etc.).
FIGS. 9A and 9B are schematic diagrams showing an example of a recording head of so-called top shooter type using thermal inkjet, which is one of such inkjets. Of FIGS. 9A and 9B, FIG. 9A is a view (hereinafter referred to as a plan view) of the recording head as seen from the ink ejection direction, while FIG. 9B is a sectional view taken along the line IVxe2x80x94IV in FIG. 9A.
As shown in FIG. 9A, in a recording head 150, a large number of nozzles 20 for ejecting the ink are formed in a state arranged in one direction (the direction perpendicular to the drawing plane of FIG. 9B). Further, in the example shown, two rows of such nozzles 20 (hereinafter referred to as nozzle rows) are provided, whereby the recording density is enhanced.
In this recording head 150, heaters (not shown) as ink ejection devices corresponding to the individual nozzles 20 and driving integrated circuits 14 for driving the respective heaters are formed on an Si (silicon) substrate 12, and further, on them, a partition wall 15 that defines individual ink flow paths to the respective nozzles 20 (heaters) and the like are laminated. Further, the nozzles 20 are formed through an orifice plate 22 laminated/stuck on the partition wall 15.
Further, in the Si substrate 12 of the recording head 150, there are formed an ink groove 152 for feeding the ink to the individual ink flow paths for a plurality of nozzles 20 and ink feed holes 154 for feeding the ink to this ink groove 152. The ink groove 152 is formed by digging down in the surface of the Si substrate 12 so as to extend in the direction of the nozzle rows, while the ink feed holes 154 are bored so as to be arranged at predetermined intervals in the nozzle row direction in a state connecting the back surface of the Si substrate 12 and the ink groove 152 to each other.
The recording head 150 as such is normally not handled in the state of the Si chip comprised mainly of the Si substrate 12, but it is mounted in a frame 24 and fitted into a head unit (e.g., a so-called cartridge) or the like of an inkjet printer.
In the frame 24, there is formed an ink flow path 26 for feeding the ink fed from an ink tank connected to the head unit to the ink feed holes 154 in the recording head 150.
In the recording head 150, the ink fed from the ink flow path 26 in the frame 24 flows into the ink feed holes 154 from the back surface side of the Si substrate 12, and then, the ink is introduced into the ink groove 152 communicating with the ink feed holes 154, flows from the ink groove 152 into the individual ink flow paths defined by the partition wall 15 so as to lead to the respective nozzles 20, and is ejected from the nozzles 20 by the heating of the heaters.
The recording head 150 in which ink ejection devices such as heaters (the devices include diaphragms for an inkjet printer of electrostatic type as referred to above apart from heaters for a thermal inkjet printer whose recording head is illustrated in the figures) are formed on the Si substrate 12 can be fabricated by employing the semiconductor manufacturing technology which utilizes film deposition techniques and photolithography.
In the recording head 150 of top shooter type as illustrated in the figures, the provision of ink feed flow paths extending through the Si substrate 12 is indispensable; ordinarily, the ink groove 152 for feeding the ink to the individual ink flow paths for the respective nozzles and the ink feed holes 154 for feeding the ink to the ink groove 152 from the back surface of the Si substrate 12 are formed as illustrated in the figures.
As the methods for the formation of the ink groove 152 and the ink feed holes 154 as such, there are known the etching process, the laser machining process, the sandblasting process, etc, any of which can be used for the processing of the Si substrate 12.
However, in case of the etching of an Si substrate, both the wet etching and the dry etching are excellent in processing accuracy but have the drawback that their processing efficiency is inferior.
The laser machining has problems that both its processing efficiency and processing accuracy are low and it requires much time since the splashes (work tailings) produced after machining need to be removed.
The sandblast is superior in processing efficiency indeed but it is disadvantageous because its processing accuracy is low and there is even a high possibility that damages such as the breakdown of the Si substrate 12 at the edges of the ink groove 152 be caused, for example, as shown in FIG. 9B since it is a grinding process utilizing impact. There is another disadvantage that, in case such damages exist, the flow of the ink does not become uniform, so that it becomes impossible to stably feed a correct amount of ink to each nozzle 20, and in addition, through the damaged portions, the ink penetrates to break the driving integrated circuits 14, etc. formed on the Si substrate 12 in some cases.
Further, the formation of the ink groove 152, etc. is normally made after the fabrication of the driving integrated circuits 14, etc., but, in case of using the sandblast process, static electricity is produced during processing, so that the insulating layers of the driving integrated circuits 14 are charged with the electricity, whereby the driving integrated circuits 14, etc. are subjected to electrostatic breakdown in some cases.
Thus, the sandblast is good in processing efficiency but has problems of its low processing accuracy and low production yield.
It is the object of the present invention to give solutions to the foregoing problems of the known art and, more particularly, to provide a liquid ejection apparatus used in an inkjet recording head or the like that is constituted in such a manner that liquid ejection units such as vibration plates vibrated by static electricity, heaters or the like are formed on a substrate composed of Si or the like, said liquid ejection apparatus having a good productivity and a good production yield, and the necessary portions thereof having a high accuracy, to provide a method of manufacturing this liquid ejection apparatus, to provide an inkjet printer using this liquid ejection apparatus as an inkjet recording head, and to provide a method of manufacturing this inkjet printer.
In order to attain the object described above, the first aspect of the present invention provides a liquid ejection apparatus comprising: a substrate having one side and another side; a plurality of nozzles formed in a member provided on the one side of the substrate; a plurality of droplet ejection units, each corresponding to one of the plurality of nozzles, the plurality of droplet ejection units being formed on a surface of the one side of the substrate; a plurality of individual flow paths, each feeding liquid to one of the plurality of nozzles, the plurality of individual flow paths being formed on the one side of the substrate; one or more front surface feed paths for feeding liquid correspondingly to the plurality of individual flow paths, the one or more front surface feed paths being formed by etching process from the surface of the one side of the substrate; and one or more back surface feed paths communicating with the one or more front surface feed paths, the one or more back surface feed paths being formed by sandblast process from a surface of the another side of the substrate.
Preferably, the plurality of individual flow paths are defined by a plurality of partition walls separating the plurality of nozzles from one another, the plurality of partition walls being formed on the one side of the substrate; and the plurality of nozzles are each bored in a member laminated on the plurality of partition walls and an expression: 5H+hxe2x89xa7Lxe2x89xa72H+h [wherein H stands for a height of each of the plurality of partition walls, h stands for a length of each of the plurality of nozzles, and L stands for a distance from an end portion of the one or more front surface feed paths that is toward each of the plurality of individual flow paths to each of the plurality of droplet ejection units] is satisfied while H is 6 xcexcm or less and h is 10 xcexcm or less.
Preferably, a thickness of the substrate is 600 xcexcm or more and a depth of each of the one or more front surface By feed paths is 20 xcexcm to 400 xcexcm.
Preferably, the liquid is ejected in a direction approximately perpendicular to a surface of the substrate.
The first aspect of the present invention provides a liquid ejection apparatus comprising: a substrate having one side and another side; a plurality of nozzles formed in a member provided on the one side of the substrate; and one or more liquid feed paths formed by sandblast process from a surface of the another side of the substrate opposite to the one side on which the plurality of nozzles are located, and formed by etching process from the surface of the one side of the substrate on which the plurality of nozzles are located.
It is preferable that the liquid ejection apparatus, further comprises a plurality of droplet ejection units, each corresponding to each of the plurality of nozzles, the plurality of droplet ejection units being formed on the surface of the one side of the substrate on which the plurality of nozzles are located; and a plurality of liquid flow paths for feeding liquid to each of the plurality of nozzles, the plurality of liquid flow paths being defined by one or more partition walls separating the plurality of nozzles from one another.
Preferably, the plurality of nozzles are bored in a member laminated on the one or more partition walls; the one or more liquid feed paths comprise one or more first feed paths formed by the etching process in the substrate and one or more second feed paths formed by the sandblast process in the substrate; and an expression: 5H+hxe2x89xa7Lxe2x89xa72H+h [wherein H stands for a height of the one or more partition walls, h stands for a length of the plurality of nozzles, and L stands for a length of the one or more first feed paths] is satisfied while H is 6 xcexcm or less and h is 10 xcexcm or less.
In order to attain the object described above, the second aspect of the present invention provides a method of manufacturing a liquid ejection apparatus which comprises: a substrate having one side and another side; a plurality of nozzles formed in a member provided on the one side of the substrate; a plurality of droplet ejection units, each corresponding to one of the plurality of nozzles, the plurality of droplet ejection units being formed on a surface of the one side of the substrate; a plurality of individual flow paths, each feeding liquid to one of the plurality of nozzles, the plurality of individual flow paths being formed on the one side of the substrate; one or more front surface feed paths for feeding liquid to the plurality of individual flow paths; and one or more back surface feed paths for feeding liquid to the one or more front surface feed paths, the method comprising: forming the one or more back surface feed paths by sandblast process from a surface of the another side of the substrate; and forming the one or more front surface feed paths by etching process from the surface of the one side of the substrate, thereby making the one or more back surface feed paths and the one or more front surface feed paths communicate with each other through the substrate.
Preferably, the one or more front surface feed paths are formed by the etching process after the one or more back surface feed paths are formed by the sandblast process.
Preferably, the one or more back surface feed paths are formed in the substrate, which is in a grounded state, after the plurality of droplet ejection units and driving devices for driving the plurality of droplet ejection units are formed on the substrate.
In order to attain the object described above, the third aspect of the present invention provides an inkjet printer comprising an ink ejection apparatus which includes: a substrate having one side and another side; a plurality of nozzles formed in a member provided on the one side of the substrate; a plurality of ink droplet ejection units, each corresponding to one of the plurality of nozzles, the plurality of ink droplet ejection units being formed on a surface of the one side of the substrate; a plurality of individual flow paths, each feeding ink to one of the plurality of nozzles, the plurality of individual flow paths being formed on the one side of the substrate; one or more front surface feed paths for feeding ink correspondingly to the plurality of individual flow paths, the one or more front surface feed paths being formed by etching process from the surface of the one side of the substrate; and one or more back surface feed paths communicating with the one or more front surface feed paths, the one or more back surface feed paths being formed by sandblast process from a surface of the another side of the substrate.
Preferably, the plurality of individual flow paths are defined by a plurality of partition walls separating the plurality of nozzles from one another, the plurality of partition walls being formed on the one side of the substrate; the plurality of nozzles are each bored in a member laminated on the plurality of partition walls; and an expression: 5H+hxe2x89xa7Lxe2x89xa72H+h [wherein H stands for a height of each of the plurality of partition walls, h stands for a length of each of the plurality of nozzles, and L stands for a distance from an end portion of the one or more front surface feed paths that is toward each of the plurality of individual flow paths to each of the plurality of ink droplet ejection units] is satisfied while H is 6 xcexcm or less and h is 10 xcexcm or less.
Preferably, a thickness of the substrate is 600 xcexcm or more and a depth of each of the one or more front surface feed paths is 20 xcexcm to 400 xcexcm.
Preferably, the ink is ejected in a direction approximately perpendicular to a surface of the substrate.
The third aspect of the present invention provides an inkjet printer comprising an ink ejection apparatus which includes: a substrate having one side and another side; a plurality of nozzles formed in a member provided on the one side of the substrate; and one or more ink feed paths formed by sandblast process from a surface of the another side of the substrate opposite to the one side on which the plurality of nozzles are located, and formed by etching process from the surface of the one side of the substrate on which the plurality of nozzles are located.
Preferably, the ink ejection apparatus further comprises: a plurality of ink droplet ejection units, each corresponding to each of the plurality of nozzles, the plurality of ink droplet ejection units being formed on the surface of the one side of the substrate on which the plurality of nozzles are located; and a plurality of ink flow paths for feeding ink to each of the plurality of nozzles, the plurality of ink flow paths being defined by one or more partition walls separating the plurality of nozzles from one another.
Preferably, the plurality of nozzles are bored in a member; laminated on the one or more partition walls; the one or more ink feed paths comprise one or more first feed paths formed by the etching process in the substrate and one or more second feed paths formed by the sandblast process in the substrate; and an expression: 5H+hxe2x89xa7Lxe2x89xa72H+h [wherein H stands for a height of the one or more partition walls, h stands for a length of the plurality of nozzles, and L stands for a length of the one or more first feed paths] is satisfied while H is 6 xcexcm or less and h is 10 xcexcm or less.
In order to attain the object described above, the fourth aspect of the present invention provides a method of manufacturing an inkjet printer comprising an ink ejection apparatus which includes: a substrate having one side and another side; a plurality of nozzles formed in a member provided on the one side of the substrate; a plurality of ink droplet ejection units, each corresponding to one of the plurality of nozzles, the plurality of ink droplet ejection units being formed on a surface of the one side of the substrate; a plurality of individual flow paths, each feeding ink to one of the plurality of nozzles, the plurality of individual flow paths being formed on the one side of the substrate; one or more front surface feed paths for feeding ink to the plurality of individual flow paths; and one or more back surface feed paths for feeding ink to the one or more front surface feed paths, the method comprising: forming the one or more back surface feed paths by sandblast process from a surface of the another side of the substrate; and forming the one or more front surface feed paths by etching process from the surface of the one side of the substrate, thereby making the one or more back surface feed paths and the one or more front surface feed paths communicate with each other through the substrate.
Preferably, the one or more front surface feed paths are formed by the etching process after the one or more back surface feed paths are formed by the sandblast process.
Preferably, the one or more back surface feed paths are formed in the substrate, which is in a grounded state, after the plurality of ink droplet ejection units and driving devices for driving the plurality of ink droplet ejection units are formed in the substrate.